The LCD (Liquid Crystal Display) has been a well-known display device for image display panel applications. For example, a color LCD panel using color LCD composes of a plurality of picture elements aligned in a matrix form wherein the light emitted from each cell corresponding to each primary color are mixed for each picture element and composes an image of the pictures.
An example of the configurations of conventional image display panels is explained with referring to the FIG. 9A, which shows the conceptual configuration of a conventional image display panel.
As shown in FIG. 9A, each one of picture elements 7 that compose the image display panel is constructed with one of three cells: a red cell 7R that transmits only red-color light, a green cell 7G that transmits only green-color light and blue cell 7B that transmits only blue-color light. They are aligned in the picture element 7 in an order of 7R, 7G and 7B from one peripheral side (as shown “A” in FIG. 9A) to another one (“A′” in FIG. 9A).
This configuration of image display panels presents a picture image in such a way that the light emitted from a backlight installed in the back side of the panel transmits each cell as 7R, 7G and 7B and the light transmitted through each cell corresponding to each primary color is mixed with other lights at each picture element and the mixed color of the lights composes the image of the pictures.
In this configuration of the image display panel, each picture element is composed with a red cell 7R, a green cell 7g and a blue cell 7B arranged in such an order, therefore the colored light balanced at the location namely a position (the center position) that viewers perceive the light emitting therefrom for each picture element 7 is close to the green cell 7G which is placed in the center of the picture element 7.
However, the center of each colored light emitted from each cell 7R, 7G or 7B is localized at about the center of each such cell. Therefore, the pseudo center of each color light is designated to the center of the whole picture element 7 that is determined after the image processing and the pseudo center is apart from the actual centers of lights as red-color, green-color and blue color lights. Therefore, the actual center of such red, green and blue colored lights deviates from the pseudo center of the picture element that would cause the blurring of the color due to the less color-mixing of such three primary colors in the picture element when the picture element composes the contours, fine lines etc. for presenting an image of a picture.
For the picture element constructed shown in FIG. 9A, such that the red cell 7R, the green cell 7G and blue cell 7B are aligned from a peripheral (as shown “A” in FIG. 9A) to the other peripheral (as shown “A′” in FIG. 9A), when a white vertical line (to the direction of the extensions of “A” peripheral and “A′” peripheral) against the black back ground is displayed a peripheral of the white line is blurred to be blue and the other to be red.
For this case, the degree of visual perceptivity in the color recognition can be regarded as depending on the difference of the color signal for each of red, green and blue colors emitted from the picture elements of the image display panel. For example, when the signal level of the red color is larger than the signal levels of the other colors, then the red color in the displayed image is emphasized for the human visual perceptivity and when the signal level of the red color is smaller than the signal levels of the other colors, then the red color in the displayed image is weakened for the human visual perceptivity. Since digital signals are usually input to image display panels, the change of the signal level steeply changes for the adjacent cells, therefore it tends that the blurring is easily made in the digital signal display applications.
For example, the color blurring is considered using a square shaped picture element that is widely used for image display panels. Letting the picture element 7 have a peripheral length L1=1 and the red cell, the green cell and blue cell be constructed with color filters that have the same colors and that are evenly arranged from a side (as “A” peripheral as shown in FGI. 9A) to the other side (as “A′” peripheral as shown in FGI. 9A), the degree of “red” emphasis ΔR (as seen red rich color) which is a deviation from the neutral level has a variation against the position from the “A” to “A′” as shown in FIG. 9B. For a homogenous color arrangement such that the color occupation against a linear position in the picture element is uniform for each color, the red color emphasis ΔR changes steeply at the boundary of between the red cell and the green cell and therefore this configuration of the picture element tends to show blurring.
Therefore one of the possibilities to remove or solve this problem is to use a smoothing filter to correct the contour so that the blurring is suppressed. However the conventional smoothing filters merely have the same filtering characteristics homogenously to three primary colors and do not shift the locations of the centers of color lights for the three primary colors. As the result, the color blurring is not sufficiently eliminated by using the smoothing filters. There is an alternative solution such that smaller sized cells are used, however such smaller cells are bound in limitations as the manufacturing difficulty and the increasing of manufacturing cost therefore the color blurring is not sufficiently solved out.